Oanh Nguyen Thi Kim, Bich Thuy Ly, Tipayarom Danutawat, Manadhar Bhai R, Prapat Pongkiatkul, Simpson Christopher D, Liu L-J Sally
Environmental Engineering and Management, Asian Institute of Technology, Pathumthani, Thailand.
Atmos Environ (1994). 2011 Jan 1;45(2):493-502. doi: 10.1016/j.atmosenv.2010.09.023.
Emission from field burning of crop residue, a common practice in many parts of the world today, has potential effects on air quality, atmosphere and climate. This study provides a comprehensive size and compositional characterization of particulate matter (PM) emission from rice straw (RS) burning using both in situ experiments (11 spread field burning) and laboratory hood experiments (3 pile and 6 spread burning) that were conducted during 2003-2006 in Thailand. The carbon balance and emission ratio method was used to determine PM emission factors (EF) in the field experiments. The obtained EFs varied from field to hood experiments reflecting multiple factors affecting combustion and emission. In the hood experiments, EFs were found to be depending on the burning types (spread or pile), moisture content and the combustion efficiency. In addition, in the field experiments, burning rate and EF were also influenced by weather conditions, i.e. wind. Hood pile burning produced significantly higher EF (20±8 g kg(-1) RS) than hood spread burning (4.7±2.2 g kg(-1) RS). The majority of PM emitted from the field burning was PM(2.5) with EF of 5.1±0.7 g m(-2) or 8.3±2.7 g kg(-1) RS burned. The coarse PM fraction (PM(10-2.5)) was mainly generated by fire attention activities and was relatively small, hence the resulting EF of PM(10) (9.4±3.5 g kg(-1) RS) was not significantly higher than PM(2.5). PM size distribution was measured across 8 size ranges (from <0.4 μm to >9.0 μm). The largest fractions of PM, EC and OC were associated with PM(1.1). The most significant components in PM(2.5) and PM(10) include OC, water soluble ions and levoglucosan. Relative abundance of some methoxyphenols (e.g., acetylsyringone), PAHs (e.g., fluoranthene and pyrene), organochlorine pesticides and PCBs may also serve as additional signatures for the PM emission. Presence of these toxic compounds in PM of burning smoke increases the potential toxic effects of the emission. For illustration, an estimation of the annual RS field burning in Thailand was made using the obtained in situ field burning EFs and preliminary burning activity data.
作物秸秆田间焚烧是当今世界许多地区的常见做法，其排放物会对空气质量、大气和气候产生潜在影响。本研究利用2003年至2006年期间在泰国进行的原位实验（11次田间分散焚烧）和实验室通风橱实验（3次堆积焚烧和6次分散焚烧），对水稻秸秆（RS）焚烧产生的颗粒物（PM）排放进行了全面的粒径和成分表征。在田间实验中，采用碳平衡和排放比方法来确定PM排放因子（EF）。从田间实验到通风橱实验，获得的排放因子各不相同，这反映了影响燃烧和排放的多种因素。在通风橱实验中，发现排放因子取决于燃烧类型（分散或堆积）、含水量和燃烧效率。此外，在田间实验中，燃烧速率和排放因子还受到天气条件（即风）的影响。通风橱堆积焚烧产生的排放因子（20±8克/千克RS）明显高于通风橱分散焚烧（4.7±2.2克/千克RS）。田间焚烧排放的大部分PM是PM2.5，其排放因子为5.1±0.7克/平方米或8.3±2.7克/千克燃烧的RS。粗颗粒物部分（PM10 - 2.5）主要由火灾扑救活动产生，且数量相对较少，因此PM10的排放因子（9.4±3.5克/千克RS）并不显著高于PM2.5。在8个粒径范围内（从<0.4微米到>9.0微米）测量了PM粒径分布。PM、元素碳（EC）和有机碳（OC）的最大部分与PM1.1相关。PM2.5和PM10中最主要的成分包括OC、水溶性离子和左旋葡聚糖。一些甲氧基酚（如乙酰丁香酮）、多环芳烃（如荧蒽和芘）、有机氯农药和多氯联苯的相对丰度也可能作为PM排放的额外特征。燃烧烟雾中的PM中存在这些有毒化合物会增加排放的潜在毒性影响。例如，利用获得的原位田间焚烧排放因子和初步燃烧活动数据，对泰国每年的水稻秸秆田间焚烧量进行了估算。
